1. Field of the Invention
The present invention relates to a multiple color image forming apparatus for reproducing an original image in a plurality of colors, more particularly, it relates to a multiple color image forming apparatus which selects the image for color mixing or non-developing.
2. Description of the Prior Art
Conventionally, a multiple color copying machine has been provided for reproducing an original in a plurality of colors by arranging a plurality of developing device into which developers of different colors are contained around a photosensitive drum, and performing a series of image forming processes such as charging, exposing, partial erasing, developing, transferring and fixing twice successively.
However, in such multiple color copying machine, a special paper feed passage and feed means for guiding a copying paper which has completed the first image forming process to the second image forming process are required, thus resulting in a large apparatus and complicated construction. Also, since the image forming process has to be passed twice, during which the copying paper is exposed to many mechanical and thermal stresses to cause rumples and curls, and results in a positional shift of image and blocking of paper.